In recent years, valve mechanism compressors have been improved in numerous ways to increase the efficiency of the compressors. However, demands have also been made from the market not only to increase the efficiency of the compressors, but also to suppress noise emission from the compressors.
The prior art compressor valve mechanism is disclosed in, for example, the Japanese Laid-open Patent Publication (unexamined) No. 3-175174.
Hereinafter, with reference to FIGS. 24, 25 and 26, the prior art compressor valve mechanism disclosed in the above mentioned Japanese Laid-open Patent Publication No. 3-175174 will be discussed.
FIG. 24 is a sectional view of the prior art valve mechanism in an assembled condition taken along the horizontal direction. FIG. 25 is a longitudinal sectional view of FIG. 24, and FIG. 26 is an exploded view of the prior art valve mechanism. In FIGS. 24 to 26, reference numeral 1 represents the valve mechanism, and reference numeral 4 represents a valve plate having two suction ports 2 and two discharge ports 3 both defined therein. A discharge reed valve 22 for selectively opening and closing the discharge ports 3 is retained within a recess 21 defined in the valve plate 4. Reference numeral 23 represents a stopper rivetted at 24 to the valve plate for regulating the lift of the reed valve 22. A suction reed valve 11, a plate-like gasket 12, the valve plate 4, a head gasket 13 and a cylinder head 14 are all bolted to a cylinder 10.
The cylinder 10 accommodates therein a piston drivingly coupled with an electric motor (not shown) for axial reciprocating movement within the cylinder 10. The cylinder head 14 has a suction chamber 25 and a discharge chamber 26 defined therein in cooperation with the valve plate 4.
The operation of the prior art compressor valve mechanism of the structure described above will now be described.
As a result of reciprocating movement of a piston 15, a refrigerant gas within the suction chamber 25 is sucked into the cylinder 10 through the suction ports 2 in the valve plate 4 during opening of the suction reed valve 11 and is subsequently compressed within the cylinder 10 before it is discharged into the discharge chamber 26 in the cylinder head 14 through the discharge ports 3 during opening of the discharge reed valve 22.
In the prior art valve mechanism discussed above, however, because the refrigerant gas is simultaneously discharged into the discharge chamber 26 through the two discharge ports 3, refrigerant gas flows interfere with each other to hinder smooth streams of the refrigerant gas, thus lowering the discharge efficiency and the performance of the compressor. Furthermore, because simultaneous discharge of the refrigerant gas from the two discharge ports 3 into the discharge chamber 26 is intermittently performed, very large pressure pulsations and noises are undesirably generated.
Also, the discharge reed valve merely has only one resonant mode as streams of the refrigerant gas discharged respectively from the two discharge ports 3 push the discharge reed valve 22 simultaneously. Therefore, it has been difficult to make resonance of the reed valve 22 proper and also to optimize the discharge efficiency at about 3,000 revolutions per minute at 50 Hz and also at about 3,600 revolutions per minute at 60 Hz. Also, even in the case of the compressor in which the number of revolutions per minute is varied such as an inverter, there has been a problem in that changes in number of revolutions per minute tend to be accompanied by considerable lowering of the efficiency.
In addition, since the discharge reed valve 22 merely has the single resonant mode, there has been another problem in that hissing sounds generated by the respective streams of the refrigerant gas discharged from the two discharge ports tend to be enhanced by interference to thereby result in considerable generation of noise.
Also, the discharge reed valve 22 is fixed in position within the recess 21 by the stopper 23 and the rivets 24, requiring a complicated mounting and an inefficient assemblage.
Japanese Patent Publication (examined) No. 6-74786 discloses a suction system for an electrically-operated sealed compressor in which a muffler having a plurality of chambers partitioned from each other is employed for muffling. However, there has been a problem in that if the muffling feature is given priority, the suction efficiency tends to be lowered accompanied by reduction in performance.
Also, since a sucked gas represents an intermittent flow as a result of selective opening and closing of a reed valve, a flow inertia of a refrigerant gas cannot be sufficiently utilized and the charge on a cylinder tends to be lowered. This tendency is enhanced when the muffling performance of the muffler is increased.
This sealed compressor requires the muffling performance of the muffler and the suction efficiency to be improved.
The present invention has been developed to overcome the above-described disadvantages.
It is accordingly an objective of the present invention to provide an improved electrically-operated sealed compressor which has a high discharge efficiency and in which sounds generated as a result of interference between discharged refrigerant gases are of a low level to accomplish noise suppression, and in which pulsation of the refrigerant gas is very small.
Another objective of the present invention is to provide an electrically-operated sealed compressor capable of accommodating changes in number of revolutions.
A still further objective of the present invention is to provide an electrically-operated sealed compressor in which the discharge valve can easily be mounted to facilitate assemblage.
Another objective of the present invention is to provide an electrically-operated sealed compressor in which the stopper and the discharge valve can easily be fixed in position.
Still another objective of the present invention is to provide an electrically-operated sealed compressor capable of improving and maintaining the compressing performance of the compressor in a muffler without lowering the flow inertia of the refrigerant even if the charge on the cylinder is improved and, hence, the muffling performance is increased.